The Corpus Juris (or Iuris) Civilis ("Body of Civil Law") is the modern name for a collection of fundamental works in jurisprudence, issued from 529 to 534 by order of Justinian I, Eastern Roman Emperor. It is also sometimes referred to as the Code of Justinian, although this name belongs more properly to the part titled Codex.

The work as planned had three parts: the Code (Codex) is a compilation, by selection and extraction, of imperial enactments to date; the Digest or Pandects (the Latin title contains both Digesta and Pandectae) is an encyclopedia composed of mostly brief extracts from the writings of Roman jurists; and the Institutes (Institutiones) is a student textbook, mainly introducing the Code although it has important conceptual elements that are less developed in the Code or the Digest. All three parts, even the textbook, were given force of law. They were intended to be, together, the sole source of law; reference to any other source, including the original texts from which the Code and the Digest had been taken, was forbidden. Nonetheless, Justinian found himself having to enact further laws and today these are counted as a fourth part of the Corpus, the Novellae Constitutiones (Novels, literally New Laws).

The legal term Corpus Juris means "body of law".

It was originally used by the Romans for several of their collections of all the laws in a certain field; see Corpus Juris Civilis.

Later the term was used for comprehensive collections of laws in the US, as in Corpus Juris Secundum. The term is commonly used to refer to the entire body of law of a country, jurisdiction, or court, such as "the corpus juris of the Supreme Court of the United States."

The phrase has been used in the European Union to describe the possibility of a European Legal Area, a European Public Prosecutor and a European Criminal Code. Eurosceptics have attacked the plans which they see as a threat to the criminal law traditions of individual member states, such as jury trials by independent juries, habeas corpus, and prohibitions against double jeopardy.